A user attempting to sign up on your platform but is unable to do so. Amidst the chaos, you are on call, attempting to debug the user service. You discover that the messaging service, upon which the user service depends, is down. You begin to question the rationale behind separating these services into different microservices if they are so tightly coupled.

What if we change our approach from the User service commanding the Messaging service to "Send a signup email to this user, I am waiting!!!!" to "A user is created with these details, do whatever you want"? Now we are thinking asynchronously and asynchronicity brings the leverage of loose coupling.

Now that we understand the purpose and benefits of event-driven architecture, we can focus on building one using AWS, completely serverless! We will explore key terminologies like "Router" and "Event Store" and their roles in our architecture. We will also examine how to reliably emit events using the "Transactional Outbox Pattern". Finally, we will connect all these components step-by-step to build an end-to-end solution.